ZSIM1GALDYN Informe resumido

Final Activity Report Summary - ZSIM1GALDYN (Merging, Outflows, or Rotation? Early galaxy evolution in the context of dark matter assembly)

Unlike many other scientists, astronomers are in a lucky position of directly witnessing most of the evolutionary history of their prime research target: the Universe. For example, we know that galaxies evolved primarily in the early universe, and that most of the star formation and galaxy assembly was already completed when the universe was about half its present age. Since we covered different cosmic epochs with our project, we were able to witness this decline in activity directly. Thanks to modern technology, and in particular the recently developed 'integral-field spectroscopy', we are now able to not only study the 'When?' but also the 'How?' of galaxy formation in the early universe. Which physical processes shaped the galaxies we see today?

As part of this project, we found that gas physics plays a major role that cannot be neglected, altering the physical gas conditions, and often even leading to galaxy-scaled 'winds' of outflowing gas. The active star formation in galaxies in the early universe may well be self-regulated, through the enormous energy output of supernovae and young stars, which may balance the further collapse of gas into giant molecular clouds and then into stars. However, in the most massive galaxies such processes are not sufficient. In these galaxies, we could show that a yet more powerful process is at work, namely winds triggered by the activity of the central supermassive black hole. These appear to be able to quench star formation in the most extreme starbursts in the universe, by removing most of the available gas, and hence the 'fuel' available to star formation. Thus, we witnessed the 'final fireworks' in the history of the most massive galaxies in the universe, which at low redshift appear 'old, red, and dead'.